1. Field
The present disclosure relates to a fuel cell.
2. Description of the Related Art
A solid polymer electrolyte fuel cell includes an electrolyte membrane electrode assembly (hereinafter may be referred to as “MEA”) constituted by an electrolyte membrane formed of a polymer ion exchange membrane, and an anode and a cathode that sandwich the electrolyte membrane. The anode and the cathode are each constituted by an electrode catalyst layer facing the electrolyte membrane and a gas diffusion layer disposed on the electrode catalyst layer.
A MEA of this type is sometimes configured as a step MEA. In a step MEA, one of the anode and the cathode includes a gas diffusion layer having a smaller surface area than the solid polymer electrolyte membrane while the other of the anode and the cathode includes a gas diffusion layer having the same surface area as the solid electrolyte membrane. In the step MEA, the outer wall of the MEA is surrounded by a resin frame member to reduce the amount of the electrolyte membrane, which is relatively expensive, to be used and to protect the electrolyte membrane, which is thin and has low strength.
Japanese Unexamined Patent Application Publication No. 2007-66766 (in particular, paragraph 0014 and FIG. 1A) discloses a fuel cell having the above-described structure. Referring to FIG. 1A of publication '766, this fuel cell includes an anode and a cathode sandwiching an electrolyte membrane, and the surface areas of the gas diffusion layer and the electrode catalyst layer of the cathode are smaller than those of the anode. The resin frame member has a recess that is indented from the lower side of the resin frame member toward the upper side of the resin frame member and an insertion hole extending from the ceiling of the recess and penetrating through the resin frame member. The anode and the electrolyte membrane are disposed in the recess and the cathode is inserted into the insertion hole.
The ceiling of the recess and the part of the electrolyte membrane protruding from the cathode and facing the ceiling are bonded to each other via an adhesive layer.